Sleeping bag



FIG. 1 is a top plan view of a sleeping bag showing my new design;

FIG. 2 is a bottom plan view;

FIG. 3 is a rear elevational view;

FIG. 4 is a left side elevational view;

FIG. 5 is a right side elevational view; and

FIG. 6 is a front elevational view. 

The ornamental design for a sleeping bag, as shown and described. 